Intervertebral disc temperature mapping during disc biacuplasty in the human cadaver.

BACKGROUND Intradiscal biacuplasty (IDB) is a novel heating therapy using cooled radiofrequency (RF), which may offer relief for discogenic pain. Effective neuroablation may be achieved intradiscally at higher lesion temperatures. The safety of intradiscal heating at elevated temperatures using cooled RF has never been reported. OBJECTIVE The purpose of this study is to map the intradiscal and peridiscal temperatures when IDB is performed at increased temperature using a modified lesion approach. The resulting temperature profiles are used to assess the safety and theoretical efficacy of this approach to ablate nociceptors in the posterior annulus. STUDY DESIGN Research article. METHODS Eleven lumbar discs in a non-perfused human cadaver were treated by IDB. Temperature profiles in the disc during bipolar lesion at 50°C followed by 2 monopolar lesions at 60°C were mapped using custom thermocouples. Temperatures inside the disc, at the nerve roots, and in the midline ventral epidural space were monitored in real-time using a data-collection system with custom RF filters. SETTING Human research laboratory. RESULTS Higher maximum temperature was reached intradiscally, and a larger volume of tissue was exposed to neuroablative temperature (> 45°C). Temperature at the nerve roots and in the epidural space increased by 2.4°C ± 2.6°C and 4.9°C ± 1.9°C (mean ± SD), respectively, during bipolar lesion. Similarly, temperature increased by 2.2°C ± 1.9°C and 0.8°C ± 1.3°C at the nerve roots and in the epidural space, respectively, during monopolar lesion. LIMITATIONS Limitations include the ex vivo setting which lacks perfusion and may not reproduce in vivo conditions such as cerebrospinal fluid dynamics. CONCLUSIONS The modified treatment paradigm showed intradiscal heating is achieved and is concentrated in the posterior annulus, suggesting minimal risk of thermal damage to the neighboring neural structures. Clinical benefits should be evaluated.